Excess air cycle engine and air supply means and method of operating same



Dec. 26, 1967 E. A. VON SEGGERN ETAL 3,359,958 EXCESS AIR CYCLE ENGINEAND ATR SUPPLY MEANS Y ,1 AND METHOD OF OPERATING SAME Original FiledAug. 1- 1963 2 Sheets-Sheet 1 Mad .@ wg w .ELMESTJQ my $5665? Dec. 26,1967 v E. A. VON SEGGERN ETAL 3,359,958

EXCESS AIR CYCLE ENGINE AND AIR SUPPLY MEANS AND METHOD OF OPERATINGSAME Original Filed Aug. 19, 1963 2 Sheets-Sheet 2 n f 42 V INVENTORS,

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United States Patent M 3,359,958 EXCESS AIR CYCLE ENGINE AND AIR SUPPLYMEANS AND METHOD OF OPERATING SAME Ernest A. von Seggern, 1051 E.Augeleno, Burbank, Calif. 91501, and Henry E. von Seggern, Rte. 2, Box1910, Escondido, Calif. 92025 Continuation of application Ser. No.303,116, Aug. 19, 1963. This application Aug. 29, 1966, Ser. No. 579,45012 Claims. (Cl. 12375) ABSTRACT OF THE DISCLOSURE An engine is providedin which separate bodies of working fluid, of which one contains, atleast, an excess of air, and the other is an ignitable and combustiblefuel-air mixture, are held in stratified relation pn'or to combustion bymeans of a system of circulation in which one body of working fluid isplaced along an axis and the other body of working fluid circulatesaround said axis in a plane substantially normal to said axis. The axisof circulation is substantially the same as the length axis of theengine cylinder. The separate bodies of fluid are introduced into thecylinder through separate manifolds each having a flow control valve,but in some forms the two bodies may enter the cylinder through a singleintake valve opening into the cylinder. Additional flow controlthrottles are also provided.

This application is a continuation of our copending application Ser. No.303,116, filed Aug. 19, 1963, entitled, Excess Air Cycle Engine and AirSupply Means and Method of Operating Same, which was acontinuation-inpart of our application, Ser. No. 296,311, filed July 19,1963, and entitled, Excess Air Cycle Engine and Air Supply Means andMethod of Operating Same, now aban doned.

This invention relates to internal combustion engines of the class whichutilize excess air in the combustion process, and in particular toengines which operate with two distinct, stratified fuel charges ofdifferent fuel-air ratios in the combustion chamber. Fuels such asgasoline or light distillate are suitable for use and ignition isgenerally by electric spark. The method of operation follows in part thebasic principles disclosed in our applications entitled, Excess AirCycle Engine, Ser. No. 278,383, filed May 6, 1963; Dual Fuel SupplyMeans for Excess Air Cycle Engine, Ser. No. 283,089, filed May 24, 1963;and Excess Air Cycle Engine and Fuel Supply Means, Ser. No. 288,- 033,filed June 14, 1963. The subject matter of these applications isincorporated herein by this reference.

It is a general object of the invention to provide an engine of the typedescribed in which fuel is burned in combination with air in excess ofstoichiometric proportions and a clean, odorless, non-smog producingcombustion is obtained. Another object is to provide an engine which iscapable of achieving higher thermal efiiciency at part load than thestandard gasoline engine, but which does not sacrifice any of theperformance or high output of the standard engine.

Another more specific object includes the provision of an engine whichemploys a standard carburetor and fuel supply means, and coordinates itsfunction with means for supplying localized air to the combustionprocess.

Additional general objects and features of the invention, as well asspecial objects and features, will be described in the specification inconjunction with the description of the specific forms shown herein.

The engines by means of which the foregoing objects are attained allcombine a fuel-air charge of substantially stoichiometric proportionswith a localized body of air, and add the air to the combustion onlyafter the burning 3,359,958 Patented Dec. 26, 1967 of the stoichiometricfuel-air mixture has been substantially completed. The burning of leanmixtures is avoided, i.e. the excess air is not added to the mixtureprior to or during the initial phase of combustion. There are twodistinct methods by which the air is kept separate from the fuelmixture. First, there is a dynamic method, in which the contents of thecombustion chamber circulate about an axial zone, with either the fuelmixture circulating around the air zone or the air circulating about thefuel zone. Secondly, there is a static method, in which the air is heldin a separate pocket or somewhat isolated zone, and the fuelmixture andair body are formed separately and held separately until combustion issubstantially completed. These two methods are also combined in whichthe fuel mixture and air are first held separately in the enginecylinder by the dynamic method, and the air is then compressed into theisolated zone during the compression cycle and held by the static methodduring the initial phase of the combustion.

The fuel mixture portion of the total charge supplied to the engine isgenerally substantially larger in volume than the air supplied, but thismay vary widely. When air is added to a fuel mixture prior tocombustion, the result is a lean, slow burning combustion with highexhaust temperatures. On the other hand, air which is added to thecombustion after the burning is nearly complete, but before substantialexpansion occurs, produces a clean, fast burning combustion with a coolexhaust.

The manner in which excess air is added and localized and coordinatedwith the stoichiometric fuel mixture varies in different forms of theengine. The features of each will be described in conjunction with thedescription of the several forms. It will be evident that, while theengines are shown with carburetors, this particular fuel supply means isnot a part of the invention, and any other known fuel supply means canbe substituted therefor. In the accompanying drawings, showing typicalillustrative embodiments of the broad invention:

FIG. 1 is a vertical section of the first form of the engine taken alongthe broken line 11 of FIG. 2;

FIG. 2 is a plan view of the engine shown in FIG. 1;

FIG. 3 is a diagrammatic vertical section of an alternate form of theengine using a single admission valve and a cylindrical combustionchamber;

FIG. 4 is a plan view of the engine shown in FIG. 3;

FIG. 5 is a diagrammatic vertical section of an alternate form of theengine using air admission ports in the cylinder;

FIG. 6 is a plan view of the engine shown in FIG. 5;

FIG. 7 is a diagrammatic vertical section of an alternate form of theengine using a method of charge localization in which the excess air isplaced at the periphery of the rotating fuel-air charge; and

FIG. 8 is a plan View of the engine shown in FIG. 7.

The first form of the engine will be described as it is incorporated ina conventional four-cycle, water-cooled, valve-in-head engine, but it isevident that air cooling or other forms of cooling may be employed andthat the principles could also be adapted to two cycle forms. In FIGS. 1and 2, a cylinder 10 with reciprocating piston 11 therein has a cylinderhead 12 fastened onto the upper end, and both cylinder head 12 andcylinder 10 are water cooled by means of jacket 13. Air inlet valve 14and an exhaust valve 15 are located in head 12 above said cylinder.

The combustion chamber 16 is formed within head 12 andis substantiallyspherical in shape, and has the intake and exhaust valves placed thereinwith inclined valve stems relative to the axis of cylinder 10 in themanner common to this class of chamber. Exhaust valve 15 opens into anexhaust port 17, and intake valve 14 opens into an intake manifold 18.Said manifold 18 is arranged tangentially relative to the cylinder 10,so that gases entering said cylinder through valve 14 flow in acircular, spiral path therein as shown by fiow line 19.

A spark plug is located substantially between said valves at a pointadjacent to the cylinder, in the line of flow of the circulating gasesin said combustion chamber. An air admission valve 21 is located betweensaid valves 14 and 15 at a point substantially on the central axis ofcylinder 10 which coincides roughly with the axis about which the gasesin said cylinder circulate. Air valve 21 is preferably set back in ashallow pocket 22 as shown, but the size of said pocket may vary fromnothing up to one whose volume is equal to one-half the total volume ofthe combustion chamber or more. A standard carburetor 23 is mounted onthe end of intake manifold 18. An air flow control valve 24 mayconveniently be placed on throttle rod 25 of said carburetor 23 and anair tube 26 connects said valve 24 and said air admission valve 21.

The engine is shown with a conventional overhead cam shaft 27 (exhaustvalve cam shaft not shown). Shaft 27 is mounted in bearing 28 and isdriven by the usual gearing or chain (not shown). A cam 29 engages inletvalve stem 30 and operates the valve in the usual manner. A second cam31 is provided, which engages rocker arm 32, mounted on pivot 33. Thisrocker arm operates valve 21, and is timed to open valve 21substantially simultaneously with intake valve 14.

When operating at full load, the engine is substantially conventional.No air is admitted through valve 21 and a standard full, unthrottledfuel charge is admitted to cylinder 10 through intake valve 14. The onlydifference from standard practice is that the charge circulates aboutthe axis of said cylinder, but this circulation is no more, generallyspeaking, than the usual flow. The spark plug is in the line of flow,but is located near the cylinder 10 instead of in the usual centralposition between the valves. As a result the maximum output andperformance of the engine is substantially equal in every respect to thestandard engine.

When idling, or at part load operation, the air flow control valve 24 onthe throttle rod 25 opens and allows air to enter the combustion chamber16 through valve 21 simultaneously with the entry of the standardfuel-air mixture from carburetor 23 through valve 14. The fuel mixturecirculates around the cylinder as shown by flow line 19, while the airenters on the axis of spin as shown by line 34. The shallow pocket 22tends to collect and confine the air after it leaves the valve, so thatit enters the combustion chamber axially and at low velocity. The airtends, therefore, to remain on the axis while the fuelair mixturecirculates around it. Such mixing as takes place forms a localized leanfuel-air mixture which is surrounded by a normal fuel-air mixture. Themotion of the piston during the intake and compression stroke does notmaterially alter the circulating pattern, but it does tend to compressthe air back into the pocket.

Near the end of the compression stroke the spark plug 20 ignites thenormal mixture, which burns quickly with normal speed and the flameconverges on the lean central core. The high temperatures cause almostinstant burning of any fuel in this localized area regardless of thefuel-air ratio, and the excess air spreads out through the entireflaming charge early in the power stroke to completely oxidize anyunburned fuel present after the burning of the conventional fuel charge.

The size of the pocket 22 may vary quite widely, and its size influencesthe manner in which the excess air is mixed with the normal charge. Whenthere is no pocket, the air collects along the central zone of thecombustion chamber. When combustion occurs this air mixes very quicklywith the main combustion, especially since it is in the central zone ofthe main charge.

When the air is confined in a large pocket, this air remains essentiallypure up to the time of ignition, except that some of the fuel charge iscompressed into the pocket.

When combustion occurs, the normal fuel charge outside the pocket burnsinitially without intermixture with excess air. This insures a fastburning combustion, which spreads through the main combustion chamber.Some of the hot gases also compress into the pocket and a combustiontakes place therein also, but a considerable quantity of hot excess airis still present. When the power stroke begins, the contents of thepocket discharge centrally downward as shown by flow line 34, and mix ina circulating, toroidal manner quickly and completely with the burnedfuel charge in the main combustion chamber as shown by flow lines 35.The excess air finishes any unfinished combustion during the powerstroke.

Air valve 24 can be designed to vary the quantity of air admitted atvarious throttle positions in any desirable manner.

When starting the engine, especially under cold conditions, the air maybe all closed off, and this may conveniently be related to the usualchoke means. The air tube 26 is extended from valve 24 up to the choke36 and a valve 37 is placed on the end of choke rod 38 as shown. Whenthe choke is closed for starting the air is closed oif, but is openedagain as soon as the choke is opened.

There are alternate ways in which the foregoing principles may becombined in an engine. FIGS. 3 and 4 show a design which differs fromthe first embodiment of the invention principally in the means by whichair is admitted to the cylinder. Instead of admitting the air through anauxiliary valve, the air enters through the intake valve simultaneouslywith the stoichiometric carbureted fuelair mixture, but is directed toflow in a different direction than the carbureted charge. It is directedtoward the region of the axis of rotation of the main carbureted chargewhile the said carbureted charge enters the cylinder tangentially.

In FIGS. 3 and 4, a cylinder 39 has a piston 40 therein, and acombustion chamber 41 at the top. Intake valve 42 and exhaust valve 42open into this chamber and are shown as vertical valves by way ofillustration. A spherical combustion chamber with inclined valves as inFIGS. 1 and 2 could be used if desired. The intake manifold 44 isarranged tangentially to the cylinder so that the fuel mixture enteringthe cylinder during the intake cycle circulates about the central axisof said cylinder as shown by flow line 45. A conventional stoichiometricfuel-air mixture is supplied to said intake manifold by a standardcarburetor 46.

An air tube 47 is provided which enters the intake manifold 44 near saidintake valve 42 in a direction substantially normal to the cylinder, andis oriented so that air will pass through valve 42 when it is open, andflow toward the center of said cylinder.

A spark plug 48 is located in said combustion chamber in the line offlow 45. During the intake cycle, the carbu'reted fuel-air charge enterscylinder 39 through valve 42 and circulates about said cylinder in acircular rotation as indicated by line 45. Simultaneously air flowsthrough tube 47 as shown by flow line 49 and collects along the centralaxis of spin of said fuel mixture. The piston then compresses the entirecharge and the outer, stoichiometric portion is ignited by plug 48, andcombustion proceedsas described in the first embodiment. The control ofair and fuel mixture is also identical to that already described. Airtube 47 may be connected to the carburetor with air flow control valvesas described in the engine shown in FIGS. 1 and 2.

This form of engine is shown without any auxiliary pocket to hold theadded air, as was shown in FIGS. 1 and 2. In this form, as well as inothers to be described later, the pocket may be added, and is indicatedin dotted outline 41a on the central axis of cylinder 39. Air suppliedto the central region of the combustion chamber 41 during the intakecycle iscompressed, to a considerable extent, into this pocket duringthe compression cycle. This localizes the air, as in the firstembodiment, so that it enters the combustion in a slightly delayedmanner after the initial combustion is completed.

At full load little or no air is added and under these conditions pocket41a is charged with a combustible fuelair mixture. If there is atendency for this charge to detonate when combustion is initiated in thecombustion chamber in the normal manner, this can be eliminated byplacing an auxiliary spark plug 48a in the auxiliary pocket 41a andigniting the fuel simultaneously with the main fuel charge. This mayalso be done in the engine of FIGS. 1 and 2 if desired, or in any of theother alternate embodiments to be described.

Another embodiment is shown in FIGS. 5 and 6, and this differs from thatshown in FIGS. 3 and 4 in the means for admitting air to the cylinder. Acylinder 50 has a piston 51 which, when at the bottom of its stroke,uncovers air ports 52. These ports are connected by a manifold 53 andthe entrance to said manifold is provided with a check valve 54. Thisvalve admits air to the manifold, but prevents backflow from saidcylinder into the atmosphere. The combustion chamber 55 is provided withthe same type intake and exhaust valves 56 and S7, tangential intakemanifold 58, spark plug 59 and carburetor 60, as in FIGS. 3 and 4.

During the intake stroke, a normal carbureted mixture enters cylinder 50as shown by flow line 61. Near the end of the intake stroke of piston51, the ports 52 are uncovered, and air enters in streams 62 whichconverge at the center of the cylinder along the axis of rotation of therotating fuel mixture. The piston then compresses the entire charge andthe spark plug ignites the outer stoichiometric fuel mixture and thecycle completes as described before. At the end of the exhaust stroke,check valve 54 prevents exhaust gases from exhausting through the airmanifold 53. Fuel and air control are the same as already described.

A further modification is shown in FIGS. 7 and 8. This embodimentdiffers from all those already described in that the ignitable,stoichiometric fuel-air mixture is collected along the axis of rotationof the mixture, and is ignited on said axis, while air is added aroundthe outside of the mixture.

A cylinder 79 has a piston 80 therein, and is shown with a sphericalcombustion chamber 81 which has inclined intake and exhaust valves 82and 83. An intake manifold 84 is provided, tangential to said cylinder,and is supplied with a normal fuel mixture by a carburetor 85. Fuel,entering the cylinder during the intake stroke, follows the flow line86, and a spark plug 87 is provided between said valves. An air tube 88opens into said intake manifold directly behind said intake valve, andis oriented to deliver air in a stream which flows adjacent the cylinderwall parallel to, but outside of the mixture, as shown by fiow line 89.A valve 90 may be provided to control the admission of air to said tube,and valve 90 is operated by rocker arm 91 which in turn is operated bycam 92 on cam shaft 93. Cam shaft 93 has another cam 94 which operatesintake valve 82.

Intake valve 82 is opened in the usual manner during the intake cycleand a stoichiometric fuel mixture is drawn into the cylinder. If valve90 is used, it may be opened late in the intake cycle, to delay theentry of air into the cylinder. But normally both fuel mixture andexcess air enter the cylinder simultaneously and the entire charge isthen compressed and the stoichiometric central core is ignited by sparkplug 87. Combustion and the control of fuel and air are the same asalready described.

In all the forms having an air tube behind the intake valve, it isdesirable, especially in multiple cylinder designs, to have the tube fitthe contour of the back of the intake valve so that the tube isautomatically closed when the intake valve is closed. This is shown inFIG. 3, where the end of tube 47 is cut in a valve seat 95 which fitsthe back side of the head of valve 42. In multiple-cylinder designs theauxiliary air tubes are branched like the intake manifold, and have acommon air inlet which is controlled by the air valves associated withthe carburetor.

It is understood that the invention is not limited to the precisestructures shown and described, but also includes such modifications asmay be embraced within the scope of the appended claims.

We claim:

1. In the operation of an internal combustion engine of the four cycletype which utilizes at least two bodies of Working fluid of differentcomposition during the engine cycle and of which one body consists of aquantity of substantially stoichiometric fuel-air mixture, and the otherbody contains air at least in excess of that contained in astoichiometric fuel-air mixture, the method of holding said bodiessubstantially separate in said engine during at least the compressioncycle prior to ignition, which includes as steps: positioning one ofsaid bodies of working fluid along an axis substantially co-axial withthe cylinder of said engine; directing the other of said bodies ofworking fluid to circulate about said axially positioned body in a pathat a larger radial distance from said axis than said axially positionedbody; maintaining said circulation while simultaneously compressing bothbodies of working fluid; and igniting said body of working fluidconsisting of a substantially stoichiometric fuel-air mixture.

2. In the operation of an internal combustion engine of the type whichutilizes a body of substantially stoichiometric fuel-air mixture and aseparate body of air during the combustion cycle, the method ofsupplying said fuel mixture and said air body to said engine andpromoting the combustion thereof, which includes as steps: directingsaid fuel-air mixture to circulate about an axis in a flow path at asubstantial radial distance from said axis and in a plane substantiallynormal to said axis during the intake cycle of said engine; supplyingsaid body of air to a partially confined region substantially co-axialwith said axis of circulation of said fuel-air mixture during saidintake cycle; compressing said fuel-air mixture and said air body duringthe compression cycle of said engine by displacement thereof along saidaxis and in a plane substantially normal to said axis; igniting saidfuel-air mixture; and directing the air from said confined region intosaid ignited and burning fuel-air mixture after the pressure of saidburning mixture has begun to fall due to expansion thereof during thepower cycle.

3. In an internal combustion engine of the type which utilizes dualbodies of working fluid of which one consists of a substantiallystoichiometric fuel-air mixture and the other of a body of working fluidwhich contains a quantity of air at least in excess of stoichiometricproportions With any fuel present therein, and which holds said bodiesseparate in the cylinder and combustion chamber of said engine at leastup to the time of ignition of the fuel-air mixture, the combination of:a cylinder; a piston in said cylinder; a cylinder head forming acombustion chamber above said piston; dual working fluid admission meansfor admitting said working fluids to said combustion chamber and saidcylinder substantially in advance of the compression cycle of saidengine; wall means associated with said admission means having anorientation to direct one of said bodies of working fluid to a positionsubstantially close to the central length axis of said cylinder;additional wall means to direct the other of said bodies of workingfluid to flow in a circulating path in said cylinder in planessubstantially normal to said length axis and around said axiallypositioned body in paths radially more distant from said axis than saidaxially positioned body; and a spark plug in said combus tion chamberlocated in a region in contact with the body of working fluid consistingof a substantially stoichiometric fuel-air mixture.

4. In an internal combustion engine of the type having dual workingfluid admission means, of which one supplies a combustible fuel-airmixture to said engine, and one supplies excess air, the combination of:a fuel-air mixture supply means, including a choke, joined to one ofsaid dual admission means; and an air flow control valve associated withsaid choke, and connected to said excess air admission means joined tothe other of said dual admission means, whereby said air is preventedfrom entering said cylinder through said air admission means when saidchoke is closed.

5. In an internal combustion engine of the type which utilizes dualbodies of working fluid, of which one consists of a substantiallystoichiometric fuel-air mixture and the other of a body of working fluidwhich contains a quantity of air at least in excess of stoichiometricproportions with any fuel present therein, and which holds said bodiesseparate in the cylinder and combustion chamber of said engine at leastup to the time of ignition of the fuel-air mixture, the combination of:a cylinder; a piston in said cylinder; a cylinder head forming acombustion chamber above said piston; an intake valve opening into saidcombustion chamber; a first intake manifold in communication with saidintake valve; a second intake manifold opening into said first intakemanifold in close proximity to said intake valve; a flow control valvein said second intake manifold adapted to open and close substantiallyin synchronism with said intake valve; wail means in combination withsaid first intake manifold to direct working fluid flowing therethroughto enter said cylinder through said intake valve in a given direction;additional wall means in combination with said second intake manifold todirect working fluid flowing therethrough to enter said cylinder throughsaid intake valve in a different direction than the flow of workingfluid entering said cylinder from said first intake manifold; andsupplying one of said bodies of working fluid to said first intakemanifold, and the other of said bodies of working fluid to said secondmanifold.

6. A combination as in claim 5, in which said flow control valve in saidsecond intake manifold is opened and closed independently of said intakevalve, but substantially during the time said intake valve is open.

7. A method of operation as in claim 1, wherein one body of workingfluid is directed to circulate about an axis at a short radial distancefrom said axis; and the other of said bodies of working fluid isdirected to circulate around said one body of circulating working fluidat a larger radial distance from said axis and in the same direction offlow.

8. A method of operation as in claim 1, wherein the axis of circulationextends into a recess wherein at least a portion of said one body ofworking fluid is retained prior to combustion.

9. A method of operation as in claim 2, wherein the air is directed intothe burning mixture in a toroidal path substantially normal to andcoaxial with said axis.

10. An internal combustion engine as in claim 3 which includes athrottle for controlling the quantity of fuelair mixture admitted tosaid cylinder; and an air flow control valve associated with said excessair admission means and connected to said throttle means; whereby saidfuel mixture and said excess air are limted in substantially directproportion when said throttle is opened and closed.

11. In an internal combustion engine of the type which holds asubstantially stoichiornetric fuel-air mixture and a body of airseparately in the cylinder of said engine prior to combustion, thecombination of: a cylinder; a piston in said cylinder; a cylinder headforming a combustion chamber above said piston; an intake valve openinginto said combustion chamber; fuel supply means for supplying a fuel-airmixture of substantially stoichiometric proportions to said cylinderthrough said intake valve; wall means for directing said mixture to flowin said cylinder in a circulating path about the central length axis ofsaid cylinder; there being a pocket in said cylinder head opening intosaid combustion chamber at a point substantially coaxial with saidcylinder; air admission valve means in said pocket; and ignition meansin said cylinder head near the periphery of said cylinder.

12. In an internal combustion engine of the type which holds asubstantially stoichiometric fuel-air mixture and a body of airseparately in the cylinder of said engine prior to combustion, thecombination of: a cylinder; a piston in said cylinder; a cylinder headforming a combustion chamber above said piston; an intake valve openinginto said combustion chamber; fuel supply means for supplying a fuel-airmixture of substantially stoichiometric proportions to said cylinderthrough said intake valve; wall means for directing said mixture to flowin said cylinder in a circulating path about the central length axis ofsaid cylinder; a nozzle in said cylinder head opening into saidcombustion chamber at a point substantially coaxial with said cylinder;there being a pocket joined to said nozzle opposite said combustionchamber; air admission valve means in said pocket; and ignition means insaid cylinder head near the periphery of said cylinder.

References Cited UNITED STATES PATENTS 1,643,396 9/1927 Trussell 123-752,240,088 4/1941 Birkigt 12375 2,242,990 5/1941 Brown l2375 2,914,04111/ 1959 Froehlich l2375 3,087,480 4/1963 Baudry 123119 WENDELL E.BURNS, Primary Examiner.

4. IN AN INTERNAL COMBUSTION ENGINE OF THE TYPE HAVING DUAL WORKINGFLUID ADMISSION MEANS, OF WHICH ONE SUPPLIES A COMBUSTIBLE FUEL-AIRMIXTURE TO SAID ENGINE, AND ONE SUPPLIES EXCESS AIR, THE COMBINATION OF:A FUEL-AIR MIXTURE SUPPLY MEANS, INCLUDING A CHOKE, JOINED TO ONE OFSAID DUAL ADMISSION MEANS; AND AN AIR FLOW CONTROL VALVE ASSOCIATED WITHSAID CHOKE, AND CONNECTED TO SAID EXCESS AIR ADMISSION MEANS JOINED TOTHE OTHER OF SAID DUAL ADMISSION MEANS, WHEREBY SAID AIR IS PREVENTEDFROM ENTERING SAID CYLINDER THROUGH SAID AIR ADMISSION MEANS WHEN SAIDCHOKE IS CLOSED.